Buggy code:
public class HashGroupify implements IHashGroupify { public static class GroupStatistics { private double averageEquivalenceClassSize ; private int maximalEquivalenceClassSize ; private int minimalEquivalenceClassSize ; private double averageEquivalenceClassSizeIncludingOutliers ; private int maximalEquivalenceClassSizeIncludingOutliers ; private int minimalEquivalenceClassSizeIncludingOutliers ; private int numberOfGroups ; private int numberOfOutlyingEquivalenceClasses ; private int numberOfOutlyingTuples ; protected GroupStatistics ( double averageEquivalenceClassSize , int maximalEquivalenceClassSize , int minimalEquivalenceClassSize , double averageEquivalenceClassSizeIncludingOutliers , int maximalEquivalenceClassSizeIncludingOutliers , int minimalEquivalenceClassSizeIncludingOutliers , int numberOfGroups , int numberOfOutlyingEquivalenceClasses , int numberOfOutlyingTuples ) { } public double getAverageEquivalenceClassSize ( ) { } public double getAverageEquivalenceClassSizeIncludingOutliers ( ) { } public int getMaximalEquivalenceClassSize ( ) { } public int getMaximalEquivalenceClassSizeIncludingOutliers ( ) { } public int getMinimalEquivalenceClassSize ( ) { } public int getMinimalEquivalenceClassSizeIncludingOutliers ( ) { } public int getNumberOfGroups ( ) { } public int getNumberOfOutlyingEquivalenceClasses ( ) { } public int getNumberOfOutlyingTuples ( ) { } } private boolean kAnonymous ; private boolean anonymous ; private int currentOutliers ; private int elementCount ; private HashGroupifyEntry [ ] buckets ; private HashGroupifyEntry firstEntry ; private HashGroupifyEntry lastEntry ; private final float loadFactor = 0.75F ; private int threshold ; private final int absoluteMaxOutliers ; private final int k ; private final RowSet subset ; private final boolean dpresence ; private final PrivacyCriterion [ ] classBasedCriteria ; private final SampleBasedPrivacyCriterion [ ] sampleBasedCriteria ; public HashGroupify ( int capacity , final ARXConfigurationInternal config ) { } @ Override public void addAll ( int [ ] key , int representant , int count , int [ ] sensitive , int pcount ) { } @ Override public void addGroupify ( int [ ] key , int representant , int count , Distribution [ ] distributions , int pcount ) { } @ Override public void addSnapshot ( int [ ] key , int representant , int count , int [ ] [ ] elements , int [ ] [ ] frequencies , int pcount ) { } @ Override public void analyze ( boolean force ) { } @ Override public void clear ( ) { } @ Override public HashGroupifyEntry getFirstEntry ( ) { } @ Override public HashGroupify . GroupStatistics getGroupStatistics ( ) { } @ Override public boolean isAnonymous ( ) { } @ Override public boolean isKAnonymous ( ) { } @ Override public void markOutliers ( final int [ ] [ ] data ) { } public void resetSuppression ( ) { } @ Override public int size ( ) { } private final HashGroupifyEntry addInternal ( final int [ ] key , final int hash , final int representant , int count , final int pcount ) { if ( ( ( subset ) != null ) && ( ! ( subset . contains ( representant ) ) ) ) { count = 0 ; } int index = hash & ( ( buckets . length ) - 1 ) ; HashGroupifyEntry entry = findEntry ( key , index , hash ) ; if ( entry == null ) { if ( ( ++ ( elementCount ) ) > ( threshold ) ) { rehash ( ) ; index = hash & ( ( buckets . length ) - 1 ) ; } entry = createEntry ( key , index , hash , representant ) ; } entry . count += count ; if ( ( subset ) != null ) { entry . pcount += pcount ; <START_BUG> if ( ( count > 0 ) && ( ( entry . count ) == 0 ) ) { <END_BUG> entry . representant = representant ; } } if ( ( entry . count ) >= ( k ) ) { if ( ! ( entry . isNotOutlier ) ) { entry . isNotOutlier = true ; currentOutliers -= ( entry . count ) - count ; } } else { currentOutliers += count ; } if ( ( ( subset ) == null ) || ( count > 0 ) ) { entry . representant = ( ( entry . representant ) < representant ) ? entry . representant : representant ; } return entry ; } private void analyzeAll ( ) { } private void analyzeWithEarlyAbort ( ) { } private void analyzeSampleBasedCriteria ( boolean earlyAbort ) { } private HashGroupifyEntry createEntry ( final int [ ] key , final int index , final int hash , final int line ) { } private boolean equalsIgnoringOutliers ( final int [ ] a , final int [ ] a2 ) { } private final HashGroupifyEntry findEntry ( final int [ ] key , final int index , final int keyHash ) { } private int isAnonymous ( HashGroupifyEntry entry ) { } private void rehash ( ) { } }

Fix:
if ( ( count > 0 ) && ( ( entry . count ) == count ) ) {